This invention relates in general to systems and devices for enabling persons to easily locate and find lost or misplaced objects or items common to a household or office environment, and more particularly to a system utilizing a wireless transmitter and a plurality of wireless receivers attachable to objects or items needing to be located at various times. Some examples of such objects or items are keys, remote-control devices for controllable electronic equipment, like television sets, VCR""s, calculators, miniature hand-held dictating machines, and other small objects.
There have been several devices heretofore known that have attempted to solve the problem of locating lost or misplaced items. The following prior art devices relate to systems and devices for object finding: A product marketed as the Magnavox remote locater; a product marketed as the Brookstone SmartFind remote control key finder; U.S. Pat. Nos. 5,638,050 and 5,686,891 relating specifically to a locating system for a remote control having a xe2x80x9chome basexe2x80x9d; and U.S. Pat. Nos. 5,204,657; 5,648,757 and 5,790,021. These prior known devices have suffered from one or more of several deficiencies.
With one recent exception, previous devices are single-use devices where only one object could be located with the system. The one recent exception is the Brookstone product which allows users to locate up to two objects. This system will not allow the user to keep track of more than two items. Also, this product only provides for key chain attachment, and does not allow for a more permanent and secure attachment to a variety of other commonly misplaced items, such as remote-control devices, cell phones, PDA""s, pagers, electronic devices, etc. This,product also suffers from the multiple system interference problem described below, and also does not provide any means to prevent the misplacement of the transmitter itself.
For systems with more than one receiver (for example, the Brookstone product), no provision is made to easily and conveniently identify which button on the transmitter corresponds to which lost object. This results in the user occasionally pressing the wrong button and locating the wrong object. This is nuisance and results in lost time and effort in retrieving an object. Further, each receiver required different circuitry to specifically respond to a selected transmitter signal.
The receiver portion of the Magnavox Remote Finder system is prohibitively large to be conveniently attached to a variety of objects. This is certainly true when attempting to attach the receiver to small objects such as key chains, but is also true for larger objects such as remote-control devices. The Magnavox receiver is approximately 3xe2x80x3xc3x972.5xe2x80x3xc3x970.75xe2x80x3 thick.
No provision is made to preclude multiple system interference in any heretofore system. That is, when two systems are operating near each other, activation of one transmitter will cause all respective receivers within range to respond with their beep tones. For example, with the SmartFind product, pressing the button for receiver number one on one transmitter will cause all receiver number one""s within range to start beeping. The claimed range of the Brookstone product is eighty feet, so this problem could often occur among apartment dwellers or people living in houses in close proximity. This, of course, is a major annoyance to the consumer owning the unintended receiver.
There is no provision made to avoid misplacing the transmitter unit. It is unreasonable to assume the transmitter will not occasionally get misplaced itself, and if no provision is made to allow the transmitter to be easily located, that, of course, defeats the whole purpose of an object finder.
Users of the present invention may conveniently keep track of a high number of commonly misplaced objects or items having receivers attached thereto. The invention as disclosed includes a transmitter that can accommodate twelve receivers all coded with different addresses, but the circuitry can be designed to accommodate any number of receivers.
The receivers are minimally sized so they can be attached in an unobtrusive manner to a variety of objects. In the present invention, the receiver is approximately 2.5xe2x80x3xc3x971.35xe2x80x3xc3x970.2xe2x80x3 thick. This is approximately half the volume of the smallest receivers on competitive products.
The receivers of the present invention are designed such that they may be attached in a semi-permanent manner (by double-sided adhesive tape or similar attachment means) to objects such as remote-control devices, PDA""s, cell phones, pagers, and other electronic devices, etc., or by using a simple plastic casing extension, the receivers are capable of being easily connected in a hanging fashion to objects such as key chains, backpacks, etc.
The system of the present invention is designed to substantially reduce the potential for multiple system interference. This is accomplished by having each transmitter button or key when pressed correspond to a relatively unique transmission data packet and constructing transmitters having different addresses or ID""s (identification). The data packet is preferably comprised of 20 bits as follows:
11111110 (headerxe2x80x94always same 8 bits)
. . . (4 bit receiver addressxe2x80x94up to 16 unique addresses possible)
0 . . . 0 (8 bit transmitter IDxe2x80x94up to 63 unique IDs)
The first 8 bits (bits 0-7) will be an identification or header to indicate the start of a valid data transmission. Each receiver will not begin to compare the data packet to its memory until it sees the valid header. Every header will be the same regardless of transmitter or receiver. The header should be seven 1""s followed by a zero. Each programmed receiver""s uniqueness is defined by the remaining 12 bits (bits 8-19) which is composed of a 4 bit word to indicate which of the 12 receivers the transmitter can look for and a 6 bit word framed by 0""s to indicate which of 63 different transmitters the receiver is coded for receiving a signal. There would be 64 possible combinations, but the design requires one bit, the null vector, to use as the receive option to the microcontroller, thereby providing 63 unique ID""s. Of the last 8 bits, the first and last bits shall always be a zero, to preclude mistaking this portion of the data packet for the header portion. Thus, the transmitter ID is 6 bits framed by two zeros, and the transmitter ID is encoded by the 6 bits in the final 8 bits of the digital data packet.
When a user buys the product, a xe2x80x9cstarter kitxe2x80x9d would be purchased that would include a transmitter and a plurality of identical receivers. Usually, three receivers are provided, although a user may use any number and even purchase more receivers, as the transmitter is capable of handling 12 receivers. The receivers are not coded for a transmitter or a selected signal from a transmitter at the time of purchase and before the battery is installed. When the user installs the battery in the receiver, it will start to beep (for example, once per second for a predetermined time), to notify the user that the receiver is waiting to be xe2x80x9ccoded.xe2x80x9d Coding to a transmitter is accomplished by the user pressing a selected receiver button switch on the transmitter. At that time the receiver will respond with a brief confirmation tone, then go silent to notify the user that the receiver has been xe2x80x9ccodedxe2x80x9d to that transmitter and a selected receiver button on that particular transmitter to be responsive to a unique address.
In the unlikely event that two systems are in close proximity that have the same transmitter address, the user may correct this problem. When button receiver switches S6 and S7 are simultaneously pressed for one second or greater, the microcontroller will use ports PB0 and PB1 to drive the audio means in the form of a piezo transducer (BZ1). It is driven in an H-bridge configuration at 4096 kHz 50% duty cycle with PB0 and PB1 alternating between VDD and ground. The user will hear a 200 mS beep and 285 mS rest with one more 200 mS beep. Thus, pressing receiver switches 6 and 7 will toggle bit 6 (MSB of the transmitter address) to change or flip its state and consequently change the transmitter ID. Bit 6 may thereafter be toggled to return the address to its first form. When the transmitter ID is changed, the user then needs to re-code each of the receivers to the new address.
The transmitter of this invention is provided with twelve buttons and a writing area for the buttons to identify twelve receivers, each of which is responsive to a unique train of digital pulses or digital address. Thus, the user is able to easily identify which button to press to locate a desired object having a given receiver coded with a unique address. This writing area will be provided with a protective plastic lens cover, similar to the identification areas provided on many household telephones to protect the written identification from the environment.
The receiver of the invention includes an improved wake-up circuit to preserve battery life. The general idea of a wake-up circuit is known, as in U.S. Pat. Nos. 5,638,050 and 5,686,891. However, the improvement in the receiver of the present invention entails the use of a serial data stream with an embedded clock to greatly improve battery life over the standard wake-up circuit as described in the two referenced patents. With the standard wake-up circuit, when the receiver wakes up it must stay on for at least twice the length of time it takes to transmit one complete bit data packet. For example, if the transmission speed is 270 baud (bits/second) and the data packet is a 20 bit string, then the time to make that transmission is 20 bits divided by 270 bits/second, which equals 0.074 seconds, or 74 msec (mS). However, the receiver must stay on for at least twice this time, because if it came on just after the first bit of the transmission, then it must wait for the remaining 19 bits to be received, then wait for the full 20 bits, because it does not start to compare the packet to what is in its memory until it detects the valid header. Thus, with the standard wake-up circuit, the receiver wake-up time must be a minimum of 148 mS. Actually, the actual wake-up time is approximately 168 mS, because an additional 20 mS is required for the microcontroller to perform the actual comparison calculation.
The use of an embedded clock in the present invention drastically improves battery life. For example, with the embedded clock, when a receiver wakes up for a predetermined period of time for every time interval to check for an incoming transmission, it must see a rising edge and a falling edge within 7.5 mS. The transmission of one bit produces a rising edge and failing edge pattern. If it does not see this structure during the wake-up period of time, it immediately goes back to sleep. So, this provides a reduction of 160.5 mS of receiver wake-up time for every wake-up period without a valid incoming transmission, which is almost 100% of the time. This feature drastically improves battery life.
Also, in the present invention, the specific transmitter serialization is provided by a network of resistors and capacitors. This allows the use of a microcontroller having a RAM, without the need for a separate memory chip. The network includes six resistors and from one up to six capacitors, and therefore 63 different transmitters can be provided, each having a unique ID by removal of one or more of the capacitors when the transmitter is manufactured. Even with the maximum 12 components, these are extremely inexpensive components compared to a memory chip used to provide different ID""s, resulting in a minimum of ten times cost savings. Also, the added components can be easily placed anywhere on the printed circuit board, whereas a memory chip is large and makes for a larger and more difficult printed circuit board layout.
The present invention is provided with a storage base to hold the transmitter when not in use. The transmitter includes a finding function if it is misplaced, wherein the storage base has a conductor that connects two corresponding metal contacts on the transmitter when it is placed in the base to assure the user the transmitter is at a home base position and not misplaced. Each time the transmitter is removed from the base, contact is broken between the contacts and a timer circuit engages. After a predetermined time, if the transmitter has not been returned to the base, a beeper will sound to alert the user that the transmitter has not been returned to the base and as to its location. If the transmitter is still not returned to the base after a second predetermined time, then a second reminder tone will sound. If still not returned after a further predetermined time, a third tone will continue to sound until the transmitter is returned to the base to defeat the timer circuit. This last tone could be similar to a smoke alarm signal, for example a small chirp once every minute until returned. This finding function may be defeated by simultaneously pressing button switches 1 and 12 for a predetermined period of time.
The storage base or cradle for the transmitter is constructed of two pieces that may have different configurations, dependent upon the desired use of the base. In one configuration, the base may be either rested or semi-permanently mounted on a horizontal surface such as a table or kitchen counter. In the second configuration, the base may be mounted in a semipermanent vertical position, such as on a wall or refrigerator front. Accordingly, this reminder feature makes it essentially impossible to misplace the transmitter.
It is therefore an object of the present invention to provide a new and improved object finder for facilitating the finding of misplaced or lost items within a household or office environment.
Another object of the present invention is in the provision of an object finder including a wireless transmitter and a plurality of wireless receivers attachable to objects wherein the transmitter is capable of easily being configured to have a large number of different ID""s, thereby substantially reducing multiple system interference with other transmitters and electronic devices.
Another object of the present invention is to provide an object finder including a wireless transmitter and a plurality of wireless receivers including an improved receiver wake-up feature that drastically improves the battery life of a receiver.
A still further object of the present invention is in the provision of an object finder having a transmitter and at least one receiver, each having circuitry using a microcontroller having a RAM, thereby eliminating the necessity to use a separate memory chip and substantially reducing the cost of the circuitry for a transmitter.
A still further object of the present invention is in the provision of an object finder having a transmitter and a plurality of receivers which includes a feature of assisting in the finding of the transmitter should it become misplaced.
Another object of the present invention is to provide an object finder including a transmitter and a plurality of receivers, wherein the transmitter includes a microcontroller capable of having one bit of the transmitter address that can be toggled to change its ID and eliminate interference with another transmitter initially having the same ID.
A still further object of the present invention is to provide an object finder having a transmitter and a plurality of receivers that are identical and codable to respond to a unique data packet from the transmitter.
A still further object of the present invention is to provide an object finder having a transmitter and a plurality of receivers that are identical and codable to respond to a unique data packet from the transmitter, and where the circuitry of the transmitter may be modified to provide a substantial number of transmitters having unique data packet identifications.
Another object of the invention is to provide an object finder having a transmitter and a plurality of receivers, wherein a home base or cradle is provided for the transmitter, and the transmitter has a finding feature that is automatically activated when removed from the base and which after a predetermined period of time energizes an audio or visual signal, and further wherein the finding feature may be selectively defeated.